TW201619986A - Capacitively balanced inductive charging coil - Google Patents

Abstract

An inductor coil includes a wire which is wound in alternating layers such that the surface area of the wire in each winding viewed from above or below the coil is substantially equal in each half of the coil defined by a line bisecting the center point in each layer. The layers are also wound in a serpentine fashion to balance the capacitance between layers. The substantially equal surface area of wire in each half of a coil layer and in adjacent coil layers results in a balanced capacitance of the coil which, in tum, results in reduced common mode noise.

Description

Capacitive balance inductor charging coil Cross-reference to related applications

This application is a non-provisional application filed on September 2, 2014, entitled "Capacitively Balanced Inductive Charging Coil", provisional application No. 62/044,957, and claims the right of the provisional application, the provisional application The disclosure is hereby incorporated herein by reference in its entirety herein.

The described embodiments relate generally to inductive energy transfer, and more particularly to inductor coil designs that can reduce noise in portable electronic devices.

Recent advances in portable computing have led to increased convenience for users of portable electronic devices. For example, mobile phones, tablets, wearable devices, laptops, etc., allow users to communicate while the user is moving. That is, the user is free to travel when using such electronic devices for communication, internet access, navigation, and other functions. The need for portable charging has begun to increase with these conveniences.

A battery charging technology is being used to charge the inductor using a wireless charger. Wireless transmission uses a magnetic field to transfer power, thereby allowing a compatible device to receive power via this induced current rather than using conductive wires and cords. Inductive charging is a method by which a magnetic field transfers power from an external charger to a mobile device such as a telephone or laptop, thereby eliminating the wired connection. Inductive chargers typically use an inductive coil to generate an alternating electromagnetic field, and a second inductive coil in the portable device takes power from the electromagnetic field and converts it back to the current to Charging batteries. The two adjacent inductor coils combine to form a power transformer.

In some cases, inductive charging can cause electromagnetic effects that are not desired by us. Conventional coil windings may create an unbalanced capacitance that can cause common mode noise that is not desired in the ground plane of the portable electronic device. "Common mode noise" is generally in the form of a coherent interference that affects two or more elements of the electromagnetic device in a highly coupled manner. This non-going noise is particularly troublesome for portable electronic devices that include touch sensors that require low noise on the ground plane for optimal operation. The result: when the portable electronic device is being charged by the inductive charging device, the use of the touch sensor and the screen may be significantly adversely affected. Therefore, in some cases, portable electronic devices may not operate effectively during charging of such inductive batteries.

Embodiments described herein include improved coil configurations that reduce capacitive losses that are not desired and that are common mode noise generated in the transmitter and receiver coils. The windings of the coils are oriented such that the surface areas of the wires on each half of the coil are substantially equal to balance the capacitive effects produced by the coils and thus substantially reduce common mode noise. The portable electronic device can be a transmitter device or a receiver device.

An embodiment may be in the form of an inductive coil comprising: a conductive wire forming at least one winding in a first planar layer, the layer comprising a center point, the at least one winding comprising: a winding a half body; and a second half of the winding adjacent to the first half; wherein: the conductive wire intersects itself at an edge of the first half and the second half such that the conductive wire in the first half One length is substantially equal to a length of the conductive wire in the second half.

Another embodiment may be in the form of an inductive coil comprising: a first layer and a second layer formed by a single continuous length of wire; wherein the first layer is defined by a center point through one of the planes a plane that is equally divided by a line; the line defines one of the first half of the first layer and a second half; the first layer includes a plurality of windings; the wire is before the intersection with itself A first winding portion is formed on the first half of the first layer; and the electric wire forms a second winding portion on the second half of the first layer after intersecting with itself.

Yet another embodiment may be in the form of a portable electronic device comprising: a housing; one or more electronic components within the housing; and an inductive coil including at least one winding formed in a planar layer a length of conductive wire, the layer comprising a center point in the planar layer, each winding comprising: a first portion substantially comprising one half of a winding as determined by a line passing through the center point parallel to the planar layer; And a second portion of the other half of the winding in the planar layer opposite the first portion; wherein the length of the wire comprising the first portion is substantially equal to the length of the wire comprising the second portion.

These and other embodiments will be understood after reading the full text.

10‧‧‧Battery Pack

11‧‧‧Inductive Energy Transfer System

12‧‧‧Charging device

13‧‧‧Portable electronic device

14‧‧‧Shell

15‧‧‧Shell

16‧‧‧Connector

17‧‧‧First interface surface

18‧‧‧Second interface surface

19‧‧‧ Receiver coil

20‧‧‧Magnetic/magnetic flux lines

21‧‧‧Transmitter coil

23‧‧‧Control circuit

24a‧‧ phantom capacitor

24b‧‧‧ phantom capacitor

24c‧‧‧ capacitor

25‧‧‧Battery

26‧‧‧Control circuit

27‧‧‧Wire winding coil

28‧‧‧Electrical wires

30‧‧‧ center point

31‧‧‧+

32‧‧‧-

33‧‧‧ Cross-section surface size / wire width

35‧‧‧The right side of the coil

36‧‧‧ left side of the coil

37‧‧‧External winding

39‧‧‧second (or lower) half of the coil

41‧‧‧ First (or upper) half of the coil

42‧‧‧ coil

43‧‧‧ points

44‧‧‧ points

45‧‧‧ line

46‧‧‧ first half of the coil

47‧‧‧second half of the coil

48‧‧‧Winding layer/coil layer

49‧‧‧Winding layer/coil layer

The invention will be understood by the following detailed description in conjunction with the accompanying drawings, in which FIG. Portable electronic device and charging device, wherein the devices are adjacent and inductively coupled; FIG. 3 is a simplified schematic cross-sectional view of the portable electronic device and charging device of FIG. 2 taken along line 3-3 of FIG. It shows the position of the inductive charging coil within the device housing and omits all other internal components for clarity; Figure 4 is a simplified block diagram of an example of an inductive charging system; Figure 5 is a simplified circuit diagram of a sample inductive charging system; a top view of a spiral wound inductor; FIG. 7 is a top plan view of a capacitive balanced inductor according to an embodiment; FIG. 8 is a side view of an inductive charging and receiving coil according to an embodiment, the figure is clear Purpose to show spaced windings; and FIG. 9 is a flow chart illustrating a method of fabricating an inductive coil in accordance with an embodiment.

Reference will now be made in detail to the exemplary embodiments illustrated in the drawings. It is to be understood that the following description is not intended to limit the embodiments to a preferred embodiment. On the contrary, the invention is intended to cover alternatives, modifications, and equivalents of the embodiments of the invention. For example, a suitable electronic device can be any portable or semi-portable electronic device ("receiver device") that can receive energy in an inductive manner, and the suitable connecting device can be any portable type that can transmit energy inductively or Semi-portable adapter or charging device ("transmitter device").

Embodiments described herein provide an inductive energy transfer system that inductively transfers energy from a transmitter device to a receiver device to charge a battery or operate a receiver device. Additionally or alternatively, the communication or control signals may be transmitted inductively between the transmitter device and the receiver device. Thus, the terms energy, power, and/or signal are intended to encompass both the transfer of energy for wireless charging, the transmission of energy as a communication and/or control signal, or the transmission of wireless charging and communication and/or control signals.

In particular, the embodiments described herein may be in the form of a charging or receiving coil for a capacitive balancing coil in an inductive charging system. This coil can have one or more windings, layers or both. As used herein, "winding" refers to a length of conductive wire that passes through a path such that a first portion of the wire is adjacent a second portion of the wire; examples of windings include forming a circular, python-shaped pattern, spiral Parts and other lengths of wire suitable for the pattern (whether geometric or otherwise). The coils are typically composed of one or more windings of wires, and some of the coils may have multiple layers, each layer being formed from one or more windings. For example, the electrically conductive wires can be wound into a spiral to form a layer of coils or coils. The electrically conductive wires may pass one or more times in a single layer or may be wound to alternate between the layers. For example, the wires can be moved from the first layer to the second layer and round trip instead of forming the entire layer or coil and then forming the next coil.

In some embodiments, the electrically conductive wires may pass by themselves at a point in the coil or layer. in In such embodiments, each half or coil or layer may have electrically conductive wires of substantially the same length or be formed from electrically conductive wires of substantially the same length. By equalizing the length of the wire between the half of the inductor (or layer of the inductor), the parasitic capacitance generated by the coil can be substantially equalized and accounted for. Therefore, the compensation for the noise generated by the coil can be simplified. Thus, the adverse effects of the inductive charging (or receiving) coil formed as described herein can be reduced, and the coil can have less impact on other components of the electronic device that have the coil.

Referring now to Figure 1, an example of an inductive energy transfer system 11 in an unpaired configuration is shown. The illustrated embodiment shows a transmitter or charging device 12 that is configured to wirelessly transfer energy to a receiver device that can be a portable electronic device 13. Although the system 11 as illustrated in Figures 1 and 2 depicts the watch as a portable electronic device, any electronic device can be configured for use with the embodiments described herein. Sample electronics that can be configured to be inductively charged as described herein include: tablet computing devices, mobile phones, computers, health monitors, wearable computing devices (eg, glasses, watches, clothing, or the like) )Wait.

In many embodiments, a wearable accessory such as the electronic device 13 as depicted in FIG. 1 can include: a controller, processor or other processing unit coupled to or in communication with the memory, one or more communications Interfaces, such as output devices for displays and speakers, such as one or more sensors for biometric and imaging sensors, and one or more input devices such as buttons, dials, microphones or touch-based interfaces. The (etc.) communication interface can provide electronic communication between the communication device and any external communication network, device or platform, such as, but not limited to, a wireless interface, a Bluetooth interface, a near field communication interface, an infrared interface, a USB interface, Wi-Fi interface, TCP/IP interface, network communication interface or any conventional communication interface. In addition to communication, the wearable device can also provide information about time, health, external connections or communication devices and/or the status, messages, video, operational commands, etc. of the software executing on such devices (and Any of the foregoing may be received from an external device.

As noted above, the electronic device 13 can include a controller 26 or other electronic component. Controller The instructions are executable and perform operations associated with the portable electronic device as described herein. Using instructions (which can be retrieved from the device memory), the controller can adjust the receipt and manipulation of input and output data between components of the electronic device. The controller can be implemented in one or more computer chips. Various architectures are available for controllers such as microprocessors, special application integrated circuits (ASICs), and the like. The controller, along with the operating system, can execute computer code and manipulate data. The operating system can be a well-known system such as iOS, Windows, UNIX, or a dedicated operating system or other system known in the art. The controller can include a memory capability to store the operating system and data. The controller can also include application software to implement various functions associated with the portable electronic device.

The electronic device 13 includes a housing 14 to enclose the electronic, mechanical, and structural components of the electronic device 13. Similarly, the outer casing 15 can enclose the electronic components of the charging device 12. In some embodiments, the electronic device 13 can have a larger cross section than the charging device 12, but this configuration is not required. In other examples, charging device 12 can have a larger cross section than the receiver device. In another example, the cross-section of the charging device and the receiving device can be substantially the same. In other embodiments, the charging device 12 can be adapted to be inserted into a charging port (not shown) in the receiving device.

In the illustrated embodiment, the charging device 12 can be connected to a power source by a cord or connector 16. For example, charging device 12 can receive power from another electronic device from a wall outlet or via a connector, such as a USB connector. Additionally or alternatively, the charging device 12 is reliably battery operated. Similarly, although the illustrated embodiment is shown by connector 16 coupled to the outer casing of charging device 12, connector 16 can be electromagnetically coupled by any suitable means. The connector 16 can be removable and can include a connector sized to fit within a void or container opening in the outer casing 15 of the charger device 12.

The electronic device 13 can include a first interface surface 17 that can interface with, align, or otherwise contact the second interface surface 18 of the charging device 12. Although shown as being substantially circular (eg, convex and concave, respectively), the interfaces 17, 18 may be rectangular, triangular, or in three or horizontal There are any other suitable shapes in the cross section. In some embodiments, the shape of the interface surfaces 17, 18 can facilitate alignment of the electronic device 13 with the charging device 12. For example, and as shown, the second interface surface 18 of the charging device 12 can be configured to have a particular shape that is paired with the complementary shape of the electronic device 13 as shown in FIG. In the current example, the second interface surface 18 can include a concave shape that follows a selected curve of the first interface surface 17. That is, the first interface surface 17 of the electronic device 13 can include a convex shape that follows a curve that is the same as or substantially similar to the concave shape of the second interface surface 18.

3 depicts a simplified schematic side cross-sectional view of the inductive energy transfer system taken along line 3-3 of FIG. 2. As discussed earlier, both the charging device 12 and the portable electronic device 13 can include electronic, mechanical, and/or structural components, and for simplicity, both are shown in blocks. For ease of illustration, the embodiment illustrated in Figure 3 omits many electronic, mechanical, and structural components.

Figure 3 shows an example inductive energy transfer system in a paired and aligned configuration. The portable electronic device 13 includes one or more receiver coils 19 having one or more windings. Likewise, charging device 12 includes one or more transmitter coils 21 having one or more windings. The transmitter coil 21 can transfer energy to the receiving coil 19 in the electronic device 13. The receiver coil 19 can receive energy from the charging device 12 and can use the received energy to perform or coordinate one or more functions of the electronic device 13 and/or supplement the charge of a battery (not shown) within the electronic device 13. Receiver coil 19 and transmitter coil 21 can have any number of columns, rows, windings, and the like.

Transmitter coil 21 and receiver coil 19 may be implemented by any suitable type of inductor, and each coil may have any of a number of shapes and sizes. As will be discussed further with respect to particular embodiments, transmitter coil 21 and receiver coil 19 may have the same number of windings or a different number of windings. Typically, the transmitter coil 19 and the receiver coil 21 are surrounded by a housing to direct magnetic flux in a desired direction (e.g., toward other coils). For ease of explanation, the housing is omitted in FIG.

4 is a schematic diagram illustrating a simplified example of an inductive charging system configuration. As shown The charging device 12 includes a power unit and a control circuit 23. The transmission coil 21 generates a magnetic field 20. The mobile device includes a battery pack 10 that includes a battery 25 and associated control circuitry 26. The receiving coil 19 receives the magnetic field 20 from the charging device 12. The receiving coil 19 has a current induced therein by the magnetic field 20 when the receiving coil 19 is positioned adjacent to the transmitting coil 21 and energizing the battery charging device 12.

Power is supplied by applying a current to the transmission coil 21, which produces a magnetic flux line 20 that allows the receiving coil 19 to receive a voltage when sufficiently close to the transmission coil 21. The voltage received in the receiving coil 19 can induce a current therein, which can recharge the battery 25 after rectification in the control circuit 26. As discussed above, the charging coil 21 and the receiving coil 19 should be sufficiently close together to enable the charging coil 21 to induce current in the receiving coil 19 via the magnetic flux 20.

Referring to Figure 5, a schematic diagram of circuitry associated with an inductive charging system is shown. Charging device 12 typically includes a power input 16. The charger device 12 typically includes a control circuit 23, which may be a switching power supply to boost the voltage and/or current frequency on the charger coil 21. The A/C current conducted through the coil 21 produces a magnetic flux line 20 that will allow the nearby receiving coil 19 to receive a voltage and the voltage can induce a current in the receiving coil 19. In some embodiments, the receiving coil 19 can be of sufficient size to accept an induced voltage from the charging coil 21 at a voltage level and frequency sufficient to allow the induced voltage to charge the battery 25 and still power other functions of the electronic device. The current induced in the receiving coil 19 can be rectified by the control circuit 26 before being supplied to the battery 25.

The coil geometry in an inductive charging system can produce parasitic or non-human capacitance, as represented by phantom capacitors 24a and 24b. These capacitors are shown in phantoms because they do not exist in reality, but represent the parasitic capacitance effects produced by coils 19 and 21 (e.g., "phantom capacitance" as will be discussed herein).

Where the resulting potential difference is present between any two adjacent conductors, any two adjacent conductors can be considered a capacitor. The capacitance is inversely proportional to the distance, resulting in a larger spacing The capacitance is so low that the conductors that are substantially in close proximity can have a higher capacitance therebetween. This stray capacitance is usually small unless the conductors are close together, cover a large area, or both. For example, stray capacitance may exist between portions of the inductor winding simply because the conductive wires are close to each other. When there is a potential difference across the windings of the inductor, the coil can function as a capacitor plate and can store charge.

In the embodiment shown in FIG. 5, parasitic capacitance can be generated by the coils 19 and 21. Furthermore, if the coil is wound in a conventional manner, the parasitic capacitance may be unbalanced. That is, the capacitance represented by capacitor 24a may be greater than the capacitance represented by capacitor 24b, or vice versa. The unbalanced capacitor can generate noise in the portable electronic device 13 that is not forgotten by the user, and the noise may interfere with the operation of various features and the functions of the portable electronic device 13, such as capacitive touch sensing and biometrics. Measurement, force sensing and other functionalities.

In a parallel plate capacitor, the capacitance is proportional to the surface area of the conductor plate and inversely proportional to the separation distance between the plates. This effect is sometimes referred to as "parasitic capacitance." In the embodiment shown in Fig. 5, the parasitic capacitance generated by the coils 19 and 21 is represented by capacitors 24a and 24b. It should be understood that such capacitors 24a, 24b are not actual physical components or structures presented in the embodiments, but rather, "phantom capacitors" that represent and model the aforementioned parasitic capacitances.

The presence of parasitic capacitance introduces the displacement current into the stray capacitance between the ground reference of the device and the earth ground reference (e.g., capacitor 24c in Figure 5). This in turn creates a voltage difference between the device ground reference and the earth ground reference. For various circuits in the portable electronic device 13, the voltage difference can appear as noise and can affect its function and/or operation. For example, capacitive touch sensors, biometric sensors, force sensors, and other circuits or structures of the portable electronic device 13 can be affected.

The effect of parasitic capacitance can be greatly reduced by driving the two terminals of the transmitter coil 21 having complementary voltages (i.e., voltages having the same amplitude and shape but opposite polarities) and ensuring that the values of the parasitic capacitors 24a and 24b are close. This can inject a current of approximately the same magnitude but the opposite sign into capacitor 24c, which in turn leads to device ground reference and ground reference There is almost no voltage difference between them.

A top view of a conventional wire winding coil 27 for an inductive charging device is shown in Figure 6, but the distance between the windings of the coil is increased to simplify the viewing and understanding of the figure. A single length of electrically conductive wire 28 (or simply "wire") is spirally wound in a conventional inductive coil 27 such that the radius of each winding of wire 28 increases from center point 30. In Figure 6, lines 34-34 and 38-38 extend through a center point 30 of coil 27, which is generally in a plane. The winding is defined as one rotation of the wire 28, beginning and ending at the intersection of two bisector radii extending from the center point of the coil 27, such as half of any other line 34-34 passing through the center of the coil. For example, wire 28 intersects line 34 at a given point on the line. A single coil winding begins at the point of intersection, continues around the coil and passes through line 34, and ends where the wire 28 crosses the same line 34 a third time.

As indicated by +31 and -32, respectively, current is conducted through the wires 28. (It will be appreciated that the direction of current flow may vary from embodiment to embodiment or during operation, and thus is not fixed.) Wire 28 has a cross-sectional surface dimension 33 that is obtained through the center point of the wire. The length of the wire is multiplied by r (one half of the wire width 33) by 2π (2πrh), where r is the wire radius, and h is the wire length) to obtain the surface area of the wire, so the longer wire length has a larger surface area. The capacitance of the wire is roughly proportional to the surface area of the wire, so the larger the surface area, the larger the capacitance.

When viewed along line 34-34, right side 35 of coil 27 includes a larger wire surface area than on left side 36. This is primarily due to the increased wire length in the outer winding 37 (compared to the smaller winding corresponding to the opposite side). That is, as the radial distance from the center 30 increases, the length of the wires 28 in each half of the winding increases. Similarly, when viewed along lines 38-38, the second (or lower) half 39 of coil 27 contains more wires than the first (or upper) half 41, and thus the surface area of wire 28 is larger. There is such an imbalance for each half of the coil 27, whether along line 34-34 or 38-38 or halving the center point 29 along any other axis. This imbalance in wire length and thus surface area is inherent in the geometry of the spiral wound coil. Because the winding extends from the center point, the radius of the winding increases. Therefore, many spiral wound inductors can have capacitors on one side higher than the other, which in turn can inject noise into the electronics and inject into the electronics. As mentioned previously, this noise can adversely affect the operation and accuracy of various sensors including capacitive sensors in electronic devices and/or charging devices.

Referring to Figure 7, an embodiment of a coil 42 is shown in which the wire 28 is wound to substantially equalize the surface area of the wire 28 included on each half of the coil 42, for example, in the first half and the second half. Between the body (or the first part and the second part). Furthermore, it should be understood that the distance between the windings of the coil is amplified to simplify the viewing and understanding of the figure. Like coil 27, coil 42 is constructed of a single length of wire wound in one or more windings to form a coil. However, in this embodiment, the wires 28 can be wound such that each winding of the coil is substantially circular and exhibits substantially the same surface area on each side of the line of the halved centers 29 (when In the top view, for example, in the orientation of Figure 7). This surface area is achieved by winding the wire 28 above or below itself to form the other half of the winding. In some cases, but not necessarily, the wires intersect themselves at the common edge of the first half and the second half. As shown at points 43 and 44, the wires 28 pass over themselves and below to form coils 42 having substantially circular and balanced windings. Thus, in some embodiments, the wires may cross themselves two or more times in each layer. Moreover, such intersections may occur at a common edge or adjacent portion of the first half and the second half. In embodiments having multiple layers formed from a plurality of windings, the electrically conductive wires may intersect themselves at a common edge of the plurality of layers. For example, the wires may intersect themselves (or more than once) in the first layer at the common edge and cross once (or more than once) with themselves in the second layer at the common edge.

In this embodiment, the line 45 drawn through the center 30 of the coil 42 produces a first half 46 and a second half 47 of the coil 42 containing wires 28 of substantially the same length. Therefore, the capacitance generated by each half of the coil 42 is equalized, and the parasitic capacitance due to the imbalance between the first half and the second half is substantially eliminated. Although the embodiment shown in FIG. 7 includes passing its own wire 28 at each winding turn ("cross"), it is easy to manufacture and In other embodiments, one or more conventional spiral windings may be interspersed with the circular windings described in this embodiment. Thus, in some embodiments, only every two, three, four, etc., windings may include an intersection. That is, conventional spiral wound windings (e.g., as shown in FIG. 6) may be alternated or interspersed with the windings shown in FIG. 7 to provide a balanced or nearly balanced capacitance.

These alternative embodiments can also reduce stray capacitance in the coil and thus reduce common mode noise. Referring to Figure 5, in these embodiments, the capacitances represented by capacitors 24a and 24b are substantially equalized, thereby reducing or eliminating common mode noise that is not desired. These embodiments can result in improved manufacturability and a reduction in the size of the resulting coil. Although the coil 42 in FIG. 7 is shown as being substantially circular, it can be any symmetrical geometry (such as square, rectangular, elliptical, etc.) or axially symmetrically shaped, with the constraint that when viewed from above, The surface area of the electrically conductive wires 28 on adjacent ones of the windings is substantially or substantially the same.

Referring to Figure 8, in another embodiment, a side view of the receiver coil 19 and the transmitter coil 21 is shown (again amplifying the distance between adjacent wires). In a conventional inductive coil, the two layers of the windings may be adjacent, as shown in Figure 8, and there may be parasitic capacitances generated between their windings. In the embodiment shown in FIG. 8, coil 19 includes two winding layers 48 and 49. The transmitter coil 21 also includes two winding layers 50 and 51. In a multilayer coil such as the embodiment shown in Fig. 8, parasitic capacitance can also be generated between layers having a single transmission or receiving coil or between layers having two coils.

For example, in some cases, between the coil layers 48 and 49 of the receiving coil 19, between the layers 50 and 51 of the transmitting coil 21, between the layer 48 of the receiving coil and the layer 51 of the transmitting coil 21, the receiving coil There may be parasitic capacitance between layer 48 and layer 50 of transmission coil 21, between layer 49 of receiver coil 19 and layer 50 of transmitter coil 21, and between layer 49 of receive coil 19 and layer 51 of transmission coil 21. By comparison, the capacitance between the closer pairs is higher than the capacitance between the more distant pairs. Thus, assuming that all features of the layer are the same, the parasitic capacitance of any given layer that is closer to the coil is higher than the parasitic capacitance of any given layer that is further away from the coil. Thus, for example, the capacitance 24a between the coil layer 48 and the layer 50 is generally lower than between the coil layer 49 and the layer 50. Capacitor 24b. This results in an unbalanced capacitance between the inductive transmission and the layers of the receiving coil and results in common mode noise generation, as discussed above, common mode noise can adversely affect certain functions of the portable electronic device.

As discussed above, the capacitance can be related to both the surface area of the conductor and the distance between the conductors. In the embodiment depicted in FIG. 8, a single length of wire 28 forming receiver coil 19 alternates in a serpentine manner within adjacent winding layers 48 and 49. The same is true for the wires 28 that form the winding layers 50 and 51 of the transmitter coil 21. For ease of reference, the adjacent windings are shown by the + and / symbols, and the order in which the windings are formed by wires (e.g., the path of the wires) is shown by a series of arrows 52/53. That is, arrows 52/53 show the order in which the windings are formed by wires 28.

This alternating winding can substantially or completely balance the capacitance between winding layers 48 and 49 and between layers 50 and 51 to substantially reduce the noise voltage formed between the device ground and ground. The same is true for embodiments with more or fewer layers and more or fewer windings.

While continuous length wires 28 are shown alternating between layers 48 and 49 in the direction of arrow 52, in another embodiment, and as indicated by arrow 53, wires 28 may be between layers and then adjacent windings The alternating stepped pattern forms a winding. As a non-limiting example, as indicated by arrow 53, the wires may alternate vertically from adjacent coil layer 50 to coil layer 51, then alternate horizontally in layer 51 between adjacent windings, and then alternately horizontally back to layer 50. This pattern can also help to balance the capacitance between the layers and/or the coils.

As discussed with respect to Figure 7, the windings of the wires 28 having a continuous length alternate in each half-winding such that the length of the wires in each winding is substantially or substantially equal across each half of the winding. In another embodiment, the winding embodiment of Figure 7 can be combined with the winding embodiment of Figure 8 for a coil containing a plurality of winding layers (such as 48/49 and 50/51 shown in Figure 8). In effect, by constructing the coil according to the embodiment shown in combination of FIG. 7 and FIG. 8, the noise generated by the stray capacitance between the system ground and the earth ground is reduced or eliminated, because the capacitor is in the coil layer. And balanced between the plurality of coil layers; therefore, the capacitance values of the phantom capacitors 24a and 24b are substantially equal.

Referring to Figure 9, a flow chart illustrating a method for fabricating an embodiment of coil 19 or 21 is shown. In operation 54, a rotating mandrel is utilized. In operation 55, the length of the conductive wire is wrapped over the mandrel. This cladding may include cladding the length of the continuous wire such that in each of the half windings, the wire passes by itself to form a substantially circular winding as described with respect to FIG. In operation 56, the wire is transferred in conjunction with the cladding operation to alternate the lengths of the continuous wires used in the alternating windings of the plurality of winding layer coils. In this operation 56, the embodiments described with respect to Figures 7 and 8 can be achieved. That is, as described with respect to Figure 7, the continuous length of wire 28 can be transferred within the winding above or below the wire 28 itself, and/or as described with respect to Figure 8, the continuous length of wire 28 can be in the adjacent layer 48/49. Or alternately interlaced in 50/51. Alternatively, operation 55 or operation 56 may be eliminated to form a coil winding in accordance with the embodiment of FIG. 7 or 8. That is, if operation 55 is eliminated, multiple winding layer coils may be produced, but the continuous wire lengths are not alternated in each of the half windings as described with respect to FIG. If operation 56 is eliminated, a single winding layer coil of alternating wire lengths in each of the half windings can be produced. In any of the above embodiments, in operation 57, the wrapped wire is formed into an inductive coil structure to be incorporated into a portable electronic device.

The foregoing description uses specific nomenclature to provide a thorough understanding of the described embodiments. It will be apparent to those skilled in the art, however, that no particular details are required in order to practice the described embodiments. Accordingly, the foregoing description of the specific embodiments described herein is presented for purposes of illustration and description. The above description is not intended to be exhaustive or to limit the embodiments. For example, while transmitter coil 21 and receiver coil 19 have been described as generally circular in shape, it should be expressly understood that the embodiments disclosed herein can be used in conjunction with coils of other geometries. Moreover, it should be understood that the discussion herein regarding, describing, or otherwise referring to an inductive charging coil is equally applicable to an inductive receiving coil. Therefore, reference to any charging coil is also intended to cover the receiving coil. It will be apparent to those skilled in the art that many modifications and variations are possible in light of the above teachings.

12‧‧‧Charging device

13‧‧‧Portable electronic device

16‧‧‧Connector

19‧‧‧ Receiver coil

20‧‧‧Magnetic/magnetic flux lines

21‧‧‧Transmitter coil

23‧‧‧Control circuit

24a‧‧ phantom capacitor

24b‧‧‧ phantom capacitor

24c‧‧‧ capacitor

25‧‧‧Battery

26‧‧‧Control circuit

Claims (20)

An inductive coil comprising: a conductive wire forming at least one winding in a first planar layer, the at least one winding comprising: a first half of the winding; and a second half of the winding, Adjacent to the first half; wherein: the conductive wire intersects itself at a common edge of the first half and the second half such that one of the lengths of the conductive wires in the first half is substantially equal to the length The length of one of the conductive wires in the second half. An inductive coil of claim 1 wherein the winding is substantially circular. The inductive coil of claim 1, wherein the winding forms a symmetrical geometry. The inductive coil of claim 1, wherein the electrically conductive wire forms at least one second planar layer disposed adjacent to the first planar layer. The inductive coil of claim 4, wherein the second planar layer is spirally wound. The inductive coil of claim 5, wherein: the first planar layer and the second planar layer both comprise a winding of the continuous length of the electrically conductive wire; and the electrically conductive wire from the first half A portion partially intersects one of the conductive wires from the second half of the second half at a common edge of the first half and the second half. An inductive coil comprising: a first layer formed from a single continuous length of wire; wherein the first layer defines a plane that is bisected by a line passing through a center point of the plane, the line defining the line a first half of the first layer and a second half; the first layer comprising a plurality of windings; The wire forms a first winding portion on the first half of the first layer before intersecting with itself; and after intersecting with itself, the wire forms a second half of the first layer The second winding portion. The inductive coil of claim 7, further comprising: a second layer formed by the single continuous length of wire; wherein the second layer comprises: a first half of the second layer; and the second layer a second half adjacent to the first half of the second layer; a surface area of the wire including the first half of the second layer is substantially equal to the second half including the second layer One of the surface areas of the wire; and the wire intersects itself between the windings. The inductive coil of claim 7, wherein the coil layers are substantially circular. The inductive coil of claim 7, wherein the coil layers form a symmetrical geometry. The inductive coil of claim 7, wherein the second coil layer is spirally wound. A portable electronic device comprising: an outer casing; an inductive charging mechanism in the outer casing and comprising: an inductive coil formed by a length of conductive wire, the inductive coil being formed into at least one in a planar layer a winding having a center point, the at least one winding comprising: a first portion substantially comprising one half of the winding as determined with respect to a line passing through the center point parallel to the planar layer; and a second portion Forming a second half of the winding in the planar layer and opposing the first portion; wherein one of the conductive wires including the first portion has a length substantially equal to the second portion Part of the length of one of the electrically conductive wires. The portable electronic device of claim 12, wherein the capacitance of one of the first portions is substantially equal to the capacitance of one of the second portions. The portable electronic device of claim 13, wherein one of the parasitic capacitances associated with the first portion is substantially equal to one of the parasitic capacitances associated with the second portion. The portable electronic device of claim 12, wherein the conductive wire intersects itself at least twice per layer. The portable electronic device of claim 12, further comprising: at least one adjacent planar layer; wherein: the two layers comprise a plurality of windings made of a continuous length of wire, the wire from the half body The wires from the second half intersect and a first half of a winding is formed in the adjacent planar layer. A method for forming an inductive coil, comprising: operating a rotating mandrel; coating a length of the wire on the mandrel; transferring the wire in conjunction with the wrapping operation to alternate the wires in adjacent layers; The wrapped wire is formed as an inductive coil. The method of claim 17, wherein the transferring comprises: winding the wire into a first half of a first winding layer; winding the wire into a second half of a second winding layer; The wire is wound into a first half of the first winding layer; wherein the wire alternates between the layers in a serpentine manner. The method of claim 17, wherein the transferring operation comprises alternating substantially each half of a wire winding such that a length of the wire comprising the first half of the winding is substantially equal to a second half of the winding comprising one of the windings The length of the wire. The method of claim 17, wherein the transferring operation comprises forming a conventional spiral wound winding in at least one of the adjacent layers.